In order to produce a high power cylindrical electrochemical cell with low electrical impedance, current production techniques comprise multiple electrically conducting tabs to be attached, normally by welding, to the electrode substrate foil at several points along the electrode length. In order to decrease the cell impedance, the number of tabs are increased accordingly.
Several conventional methods of discrete tab attachment are currently employed in the manufacture of electrochemical storage cells, electrochemical capacitors, electrolytic capacitors, dry film capacitors and similar electrical devices. Conventional methods for discrete tab attachment include removing a coating in regions on both sides of a coated electrode and welding tabs to the exposed uncoated regions, and subsequently applying an insulating cover layer over the welded tab and the exposed foil on the opposite side of the electrode from the tab. In other conventional methods, the coating removal step may be avoided by partially coating the electrode surfaces, leaving uncoated coating-free electrode edge foils. Furthermore, tabs may be adhered to or alternately, cut out and formed from uncoated electrode regions. Insulating tape may then be applied to cover the tabs in order to prevent electrical shorting at the tab edges. Conventional methods for providing electrical connection of the electrodes to the wound electrode assembly without discrete tabs include blind through welding of coating-free edge foils to a plate. Electrical connection may also be provided by holding a plate in mechanical compression against the uncoated electrode foil edges.
The inventors herein have recognized potential issues with the above approaches. Namely, with the use of discrete tabs, electrical current may be channeled to a small area of the tabs at discrete points along the electrode, creating areas that may operate at significantly higher temperature than the remainder of the electrode due to high localized ohmic heating. Furthermore, cell Amp-hour (Ah) capacity is reduced overall due to the uncoated regions for tab attachment, localized differences in the anode to cathode capacity ratio in the uncoated regions may cause localized lithium plating in the case of the Li-ion battery cell chemistry. Further still, cell manufacturing complexity is increased and manufacturing speed is decreased, requiring additional functions to accomplish the coating removal, tab welding and taping operations, and demands a greater financial investment to start up production. Further still, cell manufacturing process speed may be reduced to perform coating removal, tab welding and tab taping, thereby increasing cell manufacturing cost.
One approach that at least partially addresses the above issues includes an electrochemical storage multi-cell, comprising: a housing, including a plurality of concentric annular cell chambers; a plurality of electrochemical storage cells, wherein
each of the plurality of annular cells are positioned in one of the plurality of annular cell chambers, and the plurality of annular cells are electrically connected in series; and conductive electrolyte filling each of the annular cell chambers.
In another embodiment, a method for an electrochemical storage multi-cell, comprises positioning each of a plurality of electrochemical storage cells in concentric annular chambers of a housing, the number of the concentric annular chambers corresponding to the plurality of electrochemical storage cells; electrically connecting each of the plurality of electrochemical storage cells in series; and filling each of the annular cell chambers with conductive electrolyte.
In this way, an electrochemical storage multi-cell having a very large format and providing equivalent or improved electrical and thermal performance and reduced manufacturing costs relative to conventional electrochemical storage multi-cells is provided. Furthermore, the electrochemical storage multi-cell may be produced without welding tabs to individual electrodes, thereby reducing manufacturing time and cost. Further still, cylindrical electrochemical storage multi-cells may be produced with low impedance electrical connections between electrode foils and housing terminals, thereby allowing high power operation while reducing manufacturing cost. Further still, cylindrical electrochemical storage multi-cells with low thermal resistance in relation to one another and increased component sharing may be provided, thereby reducing the number of components and the manufacturing complexity of the electrochemical storage multi-cells, reducing the size of the electrochemical storage multi-cells per unit power, and reducing manufacturing cost (resulting from reduced number of components and handling thereof, and reduced manufacturing complexity).
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.